Lock-stitch sewing machine



Dec. 30, 1930. M. HEMLEB v 1,786,944

` LOCK STITCH SEWING MACHINE' Filed Nov. 50. 1928 2 Sheets-Sheet 1 311mm Non dftozueq Patented Dec. 30, 1930 UNITED sra'ras Nr ori-lcs p L MARTIN HEMLEB, OF ELIZABETH, NEW JERSEY, ASSIGNOR T THE SINGER MANU- FACTURING COMPANY, OF ELIZABETH, NEW JERSEY, A CORPORATION 0F NEW JERSEY Loox-STITCH SEWING Macmivn `Application filed November 30, 1928. Serial No. 322,603.

This invention relates to lock-stitch sewing machines, more particularly of the rotary-hook type having an open-sided racewayfor the bobbin-case, and has for an object to improve sewing conditions in a machine of this type, by as far as possible removing impediments to the free passage of the needle-loop about the bobbin-case and y 2 under-thread. mechanism.

According to the presentimprovement there is used a cup-shaped rotary hook having an open-sided raceway for the bobbincase, which'latter is prevented from falling out of operative position in the VVhook by means of' a .bobbin-case retainer in engagement with the outer face of the bobbin-case. With the exception of the usual interengaging tongue-and-notch rotation-restraining means on the bobbin-case and its retainer, there is a free space between the two for the passage of the outer limb of the needlekloop. The weight of the bobbin-case, when in sewing position, is supportedby the hook and no mechanical bobbin-case lifter is needed to open a needle-loop passage-way between the bobbin-case and its retainer.

The cup-shaped rotary hook member is preferably provided at its rim with a pullo'ft flange, the path of' which overhangs and .is closely adjacent the rotation-restraining tongue on the bobbin-case retainer, which tongue loosely enters'a notch in the bobbincase.l The bobbin-thread isled from the usual tension-device on the .bobbin-case upwardly through v the rotation-restraining notch in the bobbin-case and across the inner end of the rotation-restraining tongue, to the needle-hole in the throat-plate. It is thus held under control or guided at a point fice of easy threading characteristics of the closely below the top of the circular path of the pull-off'flange. To prevent the pull-oli1 flange from driving the bobbin-thread out of 'the rotation-restraining notch in the bobbin-case, the rotation-restraining tongue is formed in its end with a recess affording a pocket which retains control of the bobbinthreadwhile it is being deflected or bent by the pull-ofl` flange. As the top of this pocket is close to the path of the pull-off flange, it follows that the latter bends the bobbinthread at arather sharp acute angle during the pull-off action and pulls olf a maximum amount of bobbin-thread for a minimum width or overhang of the pull-olf flange.

After the rotary hook seizes the needle` loop and has executed about one-quarter or one-third of its loop-casting rotation, the pull-off flange in passing the needle-loop forces the outer limb of the needle-loop outwardly from the face of the bobbin-case, with theresult that the outer limb of' the needle-loop starts across the face ofthe bobbin-case at a distance outwardly from such face. This result is of no particular consequence in the case of a closed-raceway hook, since the bobbin-case of a closed-raceway hook is entirely supported-by the closed raceway 'and there is nothing in engagement with the outer face of the. bobbin-case to prevent ,free passage of the outer limb of the needlelo-op across such face at a from the latter.

In the case of anopen-sided raceway hook', however, a bobbin-case retainer engaging .the outer face of the bobbin-case is used to hold distance outwardly 'the latter i-n the hook-raceway. It thus becomes a desideratumin providing such a machine with a bobbin-thread pull-off, to take care not to impede the passage of the outer limb of the needle-loop across the face of the bobbin-case and between the latter and the bobbin-case retainer. In the presentl instance th'econdition is met by providing the bobbin-case retainer with an inclined portion lor face acting to catch the outer limb of the needle-loop and guide it between the bobbin-case and bobbin-case retainer, in the loop-casting operation. It is preferred to increase the effectiveness of the pull-ofil iange, as aboveproposed, and thus enable it to be reduced in width` with a consequent gstitching mechanism of a ysewing machine embodying the invention. Fig. 2 is a view from the left of Fig. 1. Fig.k 3 is a fragmentary vertical sectional view at the stitching point, transversely 'of the line of feed. Fig. 4 is a plan view of the rotary hookand under-thread mechanism. Fig. 5 isY a perspective View ofthe same, showing the needle-loop being drawn out. Fig. 6 is a side elevation of the parts in theposition shown in Fig. '5, Fig. 7 is an inner face View of the bobbin-case retainer. Fig. 8 is an outer face view of the bobbin-case.l Fig. 9 is a perspective view of the rotary hook, and Fig. 10 is a perspective view of the movable bobbinlcase gripper-jaw According to the preferredembodiment o't the invention illustrated, 1 represents the bed f of a sewing machine having a reciprocating needle 2, presser-foot 3, ,feed-dog 4 and throat-plate'5, all of common form. Journaled below the bed is the rotary hook-shaft 6 driven in any suitable manner so as to make `two rotations to one complete reciprocation of the needle 2.- Fixed to the .shaft 6 is the rotary hook having a cup-shaped body 7 formed with the hook-beak 8 and the internal open-sided raceway 9 which receives the l bearing rib 10, of the" bobbin-case 11 held` y in working position in the hook by the bobbin-case retainer-head 12.` Thev retainerhead 12 has a pin-shank 13 lixed iii-the upstanding retainer-arm 14 by the screw 15. The retainer-arm 14 has fixed to ita pivotshaft 16 which is journaled in the bifurcated end of the horizontal bracket 17 secured by the screw 18 tothe bed-lug 19. The pivotal mounting of the retainer 14 enables it `to be swung outwardly to dotted-line position, Fig. 1, for removal .of the bobbin-case 11 from the i hook-raceway.

The toe 20 on the retainer-arm 14, striking L the inner end-wall 21 of the slot in the arm 17 which receives the arm 14, limits the dutward motion of the retainer-arm 14'. The plate 22, screwed to the lower end lof the retainer-arm v14 and extending laterally under the bifurcations ofthe arm 17, limits thelinward motion 'of the retainer arm 14 to its full-line position, Fig. 1. The pivot-shaft 16 has xedin. one end an arm 23 carrying a' pin 24 embraced by one looped end of a bowspringf25 the other looped end o which embraces the screw-pin 26 fixed to the bracket 17. The arm 23 is so positioned that in its movement between its extreme positions, shown intfull and dotted lines, Fig. 1, it crosses a line connectingthe center ot' the shaft 16 and screw 26 an'df hence functions to yieldingly urge the retainer-arm 14 to either extreme position.

The retainer-arm 14 is locked in its inner or upright position by engagement of the shoulder 27 at the lowerend of the latch 28 with the bracket 17; the latch being pivoted at 29 in a slot 30 in they retainer-arm 14. A spring 31 coiledabout the screw 32 and disposed in the slot 30 bears against the latch 28 and urges it outwardly to latching position. By manually pressing the latch 28 inwardly, the shoulder 27 is moved entirely within the slot 30 and the retainer-arm 14 is unlocked so that it can be moved to dotted line position, Fig. 1 for removal ofthe bobbin-case 11 from the hook 7. The bobbincase 11 is formed with the usual central arbor 33 on which the bobbin 34 is journaled. The bobbin-thread t is led from the bobbin 34 under the usual tension-spring 35 and upwardly acrqss the outer face of the bobbincase 11 and-through the rotation-restraining notch 36 to the needle-hole 37 in the throatplate 5- y The rotation-restraining notch 36 in the bobbin-case is entered by a rotation-restraining tongue on the bobbin-case retainer 12, said while the jaw 39 is formed at the upper end x of a' lever 40 carrying the fulcrum-screw 41 journaled inthe retainer-head12. A spring 42 surroundingv the screw 41 lwithin a cavity in the head 12 urges the` lever 40 in a direction to move the jaw 39 into engagement with the jaw 38, as shown in F igs.4 and 7 the construction/being substantially the same as that disclosed in Fig. 7 of the U. S. patent to Hemleb No. 1,548,464 of Aug. 4, 1925.

I For pulling otll the bobbin-thread t there is secured to the hook-body 7 a pull-off flange 43 operating in a cylindrical path overhanging the retainer-head 12, as shown in Figs. 1 and 4. This flange begins just back of the throat 44 of the hook, Fig. 9, and terminates at a distance somewhat greaterthan 180 from the hook-beak 8, Fig. 2. Th'e rota-v tion-restraining tongue 38, 39 is formed at vits inner. end with a notch 45, disposed below and close vto the'path of the pull` ofil flange 43. In the embodiment illustrated, the notch 45 is formed entirely in the movable jaw-member 39 of the rotation-restraining tongue land constitutes a pocket into the corner` 46 of which the bobbin-thread t is deiected by the pull-ofi' flan e43. The pocket or notch 45,-in catching t e bobbin-thread.

prevents such thread from being driven out of the rotation-restraining notch 36 in the thread-case, by the pull-off flange 43. rlhis pocket 45 also guides or confines the bobbinthread closelyvbelow the pull-off flange 43, causing the latter to bend the bobbin-thread at an acute angle, Fig. 3, between the pocket and the needle-hole, thus pulling off the desired amount of bobbin-thread with a flange 43 of minimum width or overhang.

It is characteristic of a bobbin-thread pullolf flange of this character that it engages and deflects outwardly fromfthe hook-body both limbs of the needle-loop being drawn out by the throat 44 of the hook. This has the effect 0f enlarging the needle-loop. A minimum enlargement of the needle-loop is desirable as less needle-thread` take-up action is re- Y quired and there is less reeving of the needlethread through the eye of the needle. A. min

imum outward deflection of the needle-loop, and particularly the outer limb of the needleloop, is desirable in the present instance, since the outer limb of the needle-loop must be passed between the outer faceof the thread- Vcase 11 and the adjacent face of the retainerhead 12.

lt will be understood that this problem is not encountered in the case of a closed raceway-hook, for thelreason that the bobbincase is held in place by the closed raceway and there is nothing in engagement with the outer face of the bobbin-case which would interfere with the free passage of the outer limb of the needle-loop across the face of the bobbin-case, no matter how far outwardly of the thread-case the needle-loop may be deflected by the pull-offlange. y

In the present instance the retainer-head 12 is cut away to form an inclined face 47, Figs. 5 and 6, to catch the outer limb m of the needle-loop and guide it between the bobbincase 11 and retainer-head 12. The innerlimb n of the needle-loop is caught and held as usual by the stationary hook 48 on the threadcase while the throat 44 spreads the loop and passes it about the bobbin-case.

'llhe facel ofthe retainer-head 12 is formed below the rotation-restraining tongue 38, 39 with separated rai-sed contact faces 49 of small area which engage the bobbin-case 11 and hold it separated from the main face of the retainer-head 12, thus facilitating free' passage of the limb m of the needle-loop between the bobbin-case and retainer-head.'

'llhe contact faces 49 are connected by gently) plane of the main face the rotation-restraining notch' 36 in the 1 thread-case. Hence, when the retainer-arm 14 is moved to dotted line position, Fig. 1, the gripper-jaws 38,39 withdraw the bobbincase 11 from the hook-body 7. A bobbin-case support 51 is secured to the bracket 17 and has its upper end 52 curved concentrically with the axis of the fulcrum-shaft 16. When the gripper-jaws 38, 39 are released,.in the dotted line position of theaparts, Fig. 1, the bobbin-case 11 rests upon the support 51 and is guided by the latter during the movement of the bobbin-case into working position in the hook-body; it being unnecessary to operate the gripper jaws in this inward movement. rlhe support 51 is cut away at 53 to clear the pull-off flange 43.

When renewing the lower thread supply, it is merely necessary to draw the bobbin-thread in the usual manner under the tension spring 35 and permit it to hang free.' When the first needle-loop is cast about the bobbin-case it gathers in the bobbin-thread end and automatically draws it upwardly into the rotation-restraining notch 36 and through the vneedle-hole in the throat plate.

Having .thus set forth the nature of th invention, what l claim herein is:

1. ln a sewingmachine, in combination, a reciprocating needle, a cup-shaped rotary hook having an open-sided raceway, a bobbincase in said raceway, a bobbin-case retainer movable from sewing position adjacent said hook to open position more remote therefrom, manually operated seizing mear 3 on said retainer for removing the bobbin-case from the hook when the bobbin-case retainer is shifted to open position, and a stationary rest mounted in a fixed position to engage andsupport the bobbin-caseon the opened retainer after the bobbin-case is removed from the hook and released by said seizing means, said rest being out of engagement with the bobbin-case when the latter is in working position in said hook. 2. ln a sewing machine, a reciprocating needle, a rotary hook having an open-sided raceway, a bobbin-case in said raceway, a bobbin-case retainer, apull-off flange on said rotary hook, and a bobbin-case support mounted below and independent of said retainer, said support being cut awav below its upper end to clear said pull-,off flange.

3. In a sewing machine, a reciprocating needle, a rotary hook having an open-sided raceway, a bobbin-case disposed in said raceway and formed with a rotation-restraining notch, a shiftable bobbin-case retainer having a rotation-restraining tongue entering said notch, said tongue being constituted by relabobbin-case on the opi-cned retainer when the bobbin-case is removed from the hook and releasedby said gripper-jaws, said rest being out of engagement with the bobbin-case when the latter is in working position in said hook. 4. In a sewing machlne, a reclprocating needle, a, rotary hook having*A a cup-shaped loop while the latter is being distended by the hook, `said retainer being shaped to engage the deflected outer limb of the lneedle-loop body `formed with an open-sided raceway, a

bobbin-case journaled in said raceway and formed with a rotation-restraining notch, a

bobbin-caseretainer engaging the outer face of said bobbin-case and havlng a rotationrestraining tongue entering said notch, said tongue having a bobbin-thread' pocket, and a bobbin-thread pull-off flange on said rotary hook body acting to deflect the bobbinthread into said pocket during the pull-ofiI action.

In testimony whereof, I have signed my7 name to this specification.

Y MARTIN. HEMLEB.

between the throat ofthe hook and the pulloil flange and guide such limb between said retainer and bobbin-'casa' 5. In a sewing machine, a reciprocating needle, a, rotary hook having a cup-shapedbody formed with an open-sided raceway and making two rotations for each reciprocation ,f

of said needle, a bobbin-case in said raceway,

a bobbincase retainer engaging -the outer face of said bobbin-case, and a bobbin-thread pull-olfv on said `rotary hookbody, sald' retain'er having an inclined face adapted to catch the outer limb of the needle-loop'between the thrcatof the hook and the pull-off iiange and guide such limb between the bob- ,bin-case and bobbixi-case retainer.

6. In a sewing machine, a reciprocating needle; a.l rotary hook having a cup-shaped body formed with an open-sided raceway and making two. rotations for each recipiiocation of said needle, a bobbin-case in said. raceway,

a bobbin-case retainer having a face engagingthe outer face of the bobbin-case and shiftable to permit removal of the bobbin-case from the open raceway in the hook-body, and

a bobbin-thread pull-off flange on the hookbody operating in a circular path overhanging said retaier, the face of said retainer having agout-away portionadapted to\receive `one limb of the needle-loop extending between the hook and pull-olf flange .and guide it between said retainer and said bobbin-case. 7. In a sewing machlne, a reciprocating i needle, a throat-plate, a rotary hook having having atong'ue entering said notch, said eis a cup-shaped vbody formed with an opensided raceway, a bobbin-case disposed in said raceway and formed with arotation-restrainf ing notch, a rotatlon-restralning element tongue being formed with a bobbin-thread pocket, and' a bobbin-thread pull-0E device carried by said rotary hook body and acting on the bobbin-thr'ead between said pocket and the throat-plate.

8. In a sewing machine, a reciprocatinneedle, a rotary hook having a, cup-shaped 

